High intensity focused ultrasound for imaging and treatment of arrhythmias

Abstract

A dual-mode, capable of imaging and ablation, ultrasound array integrated in a catheter is provided for minimally invasive treatment of arrhythmias. The catheter array is small enough for insertion through a peripheral vein and is longitudinally integrated with the catheter to have a side-view for tissue imaging and ablation. A high length/width array ratio creates a large aperture necessary for high power ablation densities. A catheter stabilization device maintains a distance between the catheter array and the wall of a heart or vein. Visualization of anatomy and imaging of ablated tissue provides a guide for placing the lesion and assists in achieving a pattern of ablated tissue. The catheter is advanced to another area by catheter rotation and/or array steering or focusing. Gating the imaging and ablation processes to a heart cycle allows for accounting and compensation of heart motion and enables automation of an arrhythmia treatment.

1 . An apparatus for minimally invasive treatment of an arrhythmia, comprising: 
 (a) a catheter; and    (b) a dual-mode high intensity focused ultrasound array with an ablation mode and an imaging mode, wherein said array is integrated in the longitudinal direction of said catheter, wherein said array having a side-view with respect to said catheter, and wherein said catheter is small enough to be inserted through a peripheral vein.    
   
   
       2 . The apparatus as set forth in  claim 1 , wherein said catheter has a diameter of up to 4 mm.  
   
   
       3 . The apparatus as set forth in  claim 1 , wherein said catheter has a diameter of up to 3 mm.  
   
   
       4 . The apparatus as set forth in  claim 1 , wherein said array has a length/width ratio of at least 5.  
   
   
       5 . The apparatus as set forth in  claim 1 , wherein said array has a length/width ratio of at least 15.  
   
   
       6 . The apparatus as set forth in  claim 1 , further comprising a stabilization device for said catheter to maintain a distance between said catheter array and the wall of a heart or the wall of a vein.  
   
   
       7 . The apparatus as set forth in  claim 6 , wherein said stabilization device is positioned near or in the pulmonary vein of said heart.  
   
   
       8 . The apparatus as set forth in  claim 1 , wherein said array is a 1-D array or a 2-D array of 32 or more dual-mode ultrasound transducer elements.  
   
   
       9 . The apparatus as set forth in  claim 1 , wherein said array in ablation mode has a power density at the focal area or point of a treatment area of at least 200 W/cm 2 .  
   
   
       10 . The apparatus as set forth in  claim 1 , wherein said catheter is positioned in the left atrium of a heart and said arrhythmia is an atrial fibrillation.  
   
   
       11 . The apparatus as set forth in  claim 1 , further comprising a processing means to: 
 (i) obtain an image of a region of interest in said imaging mode;    (ii) evaluate said obtained image and determine a treatment area;    (iii) determine ablation parameters for said treatment area;    (iv) focus and steer the elements in said array to said treatment area; and    (v) ablate the tissue of said treatment area in said ablation mode.    
   
   
       12 . The apparatus as set forth in  claim 11 , further comprising a heart cycle monitoring means to monitor the heart cycle and to coincide the timing and execution of said processing means within a time frame of a heart cycle.  
   
   
       13 . The apparatus as set forth in  claim 11 , further comprising a gating processor to gate (i)-(iv).  
   
   
       14 . A method for minimally invasive treatment of an arrhythmia, comprising the step of: 
 (a) inserting through a peripheral vein into a heart a catheter with an integrated dual-mode high intensity focused ultrasound array, wherein said array has an ablation mode and an imaging mode, wherein said array is integrated in the longitudinal direction of said catheter, and wherein said array having a side-view with respect to said catheter;    (b) obtaining an image of a region of interest in said imaging mode;    (c) evaluating said obtained image and determine a treatment area;    (d) determining ablation parameters for said treatment area;    (e) focusing and steering the elements in said array to said treatment area; and    (f) ablating the tissue of said treatment area in said ablation mode.    
   
   
       15 . The method as set forth in  claim 14 , further comprising repeating steps (b)-(f) for another region of interest to create a pattern of ablated tissue.  
   
   
       16 . The method as set forth in  claim 15 , wherein said pattern results in a continuous pattern of ablated tissue.  
   
   
       17 . The method as set forth in  claim 14 , wherein said catheter has a diameter of up to 4 mm.  
   
   
       18 . The method as set forth in  claim 14 , wherein said catheter has a diameter of up to 3 mm.  
   
   
       19 . The method as set forth in  claim 14 , wherein said array has a length/width ratio of at least 5.  
   
   
       20 . The method as set forth in  claim 14 , wherein said array has a length/width ratio of at least 15.  
   
   
       21 . The method as set forth in  claim 14 , further comprising stabilizing said catheter to maintain a distance between said catheter array and the wall of a heart or the wall of a vein.  
   
   
       22 . The method as set forth in  claim 21 , wherein said catheter is stabilized near or in the pulmonary vein of said heart.  
   
   
       23 . The method as set forth in  claim 14 , wherein said array is a 1-D array or a 2-D array of 32 or more dual-mode ultrasound transducer elements.  
   
   
       24 . The method as set forth in  claim 14 , wherein said array in ablation mode has a power density at the focal area or point of a treatment area of at least 200 W/cm 2 .  
   
   
       25 . The method as set forth in  claim 14 , wherein said catheter is positioned in the left atrium of a heart and said arrhythmia is an atrial fibrillation.  
   
   
       26 . The method as set forth in  claim 14 , further comprising gating said steps (b)-(f).  
   
   
       27 . The method as set forth in  claim 14 , further comprising monitoring a heart cycle and coinciding the timing and execution of said steps (b)-(f) within a time frame of said heart cycle.